HMRC's banking service, operated by Citibank, appeared to buckle under the
weight of £1m-a-minute tax payments on the self-assessment deadline today

Taxpayers rushing to settle tax bills at the last minute - today is the deadline - found the payments they make to HMRC's account were bouncing back.

The self-assessment system has been strained this year due to 630,000 middle class recipients of child benefit being required to repay the welfare payments, with many entering the process for this time.

Other payments in and out of accounts with Citibank, which is the bank handling HMRC's businesses, were also affected. The Telegraph first learned of the problem when one reader tried to make a payment from a Citibank account into a NatWest one - only for the payment to fail.

The problem was not with the "faster payment" system, the electronic network established in 2008 to allow rapid payment between banks - but with Citibank's own systems. The Payments Council, the body overseeing the network, told the Telegraph: "The Faster Payment Scheme is operating normally today. However, Citibank have let us know they are experiencing very high volumes of incoming Faster Payments, due to the HMRC tax deadline, and are asking for patience when submitting a payment."

HMRC said that earlier today it was receiving payments at the rate of £17,000 per second - just over £1m per minute - but that rate may have increased as the day has drawn on.

Several billion pounds will be paid into HMRC coffers today, it said, with record numbers of small transactions being made by individual taxpayers.

The growth in transaction numbers is due both to more people using online banking to settle their bills, as well as more individuals having to pay this year because of changes introduced to child benefits.

An HMRC spokesman said: "Today is the biggest logistical transfer of money in the calendar. We ask taxpayers to be patient and keep trying."

There will be "no penalties" for those who are trying to pay today but cannot due to this problem, he added.

Last night a Citibank spokesman confirmed the payments system had been restored. “We apologise that there were some issues making payments at certain peak times today," he said. "Citi's systems are now operating normally and the bank is currently processing all payments without issue. We have been coordinating through the Faster Payments scheme to ensure taxpayers have received the appropriate advice."